EMMA ALBERICI, PRESENTER: Turning back to our top story: the unfolding military crisis in Crimea in southern Ukraine and the Russian president's defiance against a growing tide of condemnation from the West.

For a perspective on just what kind of response we can expect from the United States and its allies, we're joined from New York by Rajan Menon, a political scientist at the City College of New York. Professor Menon has written extensively on Russia, Ukraine and Crimea.

Professor Menon, thank you very much for joining us.

RAJAN MENON, PROF. OF POLITICAL SCIENCE, CCNY: You're welcome.

EMMA ALBERICI: So we've heard president Obama saying that Russia can't violate basic principles recognised around the world. And essentially the same has come back from the Russian president, with Vladimir Putin saying that the government now in Kiev is illegitimate.

So who's likely to be winning this war of words?

RAJAN MENON: Well, at this point what you have is two leaders talking past each other. Mr Obama is under enormous pressure here in the US to do something to make Mr Putin stand down. Mr Putin, having taken the steps that he's taken, is under great pressure to keep up the activity and show that he's not backing down.

So this has a long way to go before it plays out, I'm afraid.

EMMA ALBERICI: And so how do you rate president Obama's response to Russia so far?

RAJAN MENON: Well, on the ground the Russians have such a military advantage that those who are calling for anything by way of a show of force ought to have their head examined.

On the other hand, the president has to take some steps. As far as I know this morning, there have been talks about targeted economic sanctions. We hear that there are going to be possibly, if this doesn't work, travel bans and asset freezes.

The difficulty the president faces is that many European countries have suggested they will not go along and Europe does about 10 times the trade with Russia that the US does.

One final point: it's not as if the Russians are not paying a price for this. Their stock market is down significantly. They've spent about $20 billion propping up the rouble. They've raised interest rates. And the longer this goes on, the more the pressure will hit the Russian economy. But I don't think ultimately that that will sway Mr Putin.

EMMA ALBERICI: Let's talk about the economics shortly but I just want to stay for a moment on the politics.

What's curious in this instance is that there appears to be little to no appetite in the US for a more aggressive military-style response from president Obama. Even the Republican John McCain, who led the push for some kind of US army assault in Georgia six or so years ago, is now urging caution?

RAJAN MENON: Indeed. There are a lot of people here who have argued that this crisis broke out because of president Obama's weakness. I think frankly that's nonsense.

So when tough action is called for and you press individuals who say that and ask them, "Well, what precisely should be done?", they don't have very good answers because of what I said about the military situation on the ground.

Economic and political pressure is the only way forward. The difficulty is that you need to do this in a coordinated way. Now coming to Europe, which is a key partner in this, there are 28 countries and obviously there's a collective action problem.

In a sense it's a paradox. Mr Putin, although he stands largely alone, has the advantage because he doesn't have a collective action problem.

EMMA ALBERICI: After speaking with the Russian president, German chancellor Angela Merkel said he'd lost touch with reality and that he was in another world. If she's right, is it fair to assume that Mr Putin's intentions in Ukraine don't stop in Crimea and that, in fact, what he says isn't necessarily what he's going to do?

RAJAN MENON: Well, you've asked the $64 million question. On the question of whether he's seeing reality as it is: you know, one of the things we know about crises like this - i.e. short time horizon, great pressure, fear of war - is that leaders tend to be in their own cognitive bubble, as it were.

Now, your second point about where this would go in terms of escalation: we have to watch eastern Ukraine. And if Russian troops cross the border, which I rather doubt because there's been a military exercise and they have de-escalated and pulled back, that will certainly raise the temperature in a significant way. My own sense at this point is that Putin has the advantage in Crimea. He's gotten everybody's attention and that's where he will stake his battle.

EMMA ALBERICI: Now we know the Pentagon has suspended defence cooperation with Moscow. How significant is that cooperation?

RAJAN MENON: Well, there are exchanges, military to military or "mil to mil" as we call it here, but in the grand scheme of things, if you're asking is this going to be the kind of pressure that get Mr Putin's attention, I rather suspect not. Just as, for example, threats to boycott the G8 meeting in Sochi will not get his attention. That doesn't happen until June.

EMMA ALBERICI: What about simply expelling him from the G8 group of countries? Certainly that would take a little gloss off the Russian international reputation at the very least?

RAJAN MENON: Certainly. The question there is getting the consensus among the other partners. So there's been an agreement to put on hold preparations for Sochi. But Mrs Merkel, yesterday, I believe, made it quite clear that she's not in favour of expelling Mr Putin. And without Germany onboard it's going to be very difficult to even achieve that; i.e. the expulsion of Russia.

EMMA ALBERICI: Before we talk specifically about Europe and just staying with the US, Vladimir Putin says Russia can reduce its dependence on the US to zero. Is that true?

RAJAN MENON: Well, I don't know about zero. But as I mentioned, the two-way trade is about $40 billion. Now in international terms that's not very much. By comparison Europe's is about $460 billion, more than 10 times as much.

The other problem is that while Europe's dependence on Russian natural gas has indeed declined over the past several years, about 25 per cent on average in the EU comes from Russia. And there is a country-to-country variation, i.e. some countries importing even more of their needs from Russia. So it's not as if Mr Putin doesn't have counter-pressure.

EMMA ALBERICI: Some Republicans in the US are suggesting the White House revive plans for a NATO missile defence shield in Poland. Is that a realistic option at this stage?

RAJAN MENON: Well, the problem we face here is not a Russian nuclear attack or even a conventional missile attack, so yes. I mean, if you have missile defences in Poland it might send some kind of symbolic message. But as for what it will do regarding the situation at hand, I don't think very much.

EMMA ALBERICI: And do you think Russia has anything to fear from the UN Security Council? We see that it's held its third emergency session in the last few hours or so. What is the point of those discussions, particularly given that Russia holds a veto there?

RAJAN MENON: Good point. It's important to keep talking with the Russians but public diplomacy is probably not the best way to go because you have, we'll have on all sides a great deal of theatrics.

You're right that the Russians have a veto in the Security Council. The Chinese will at the very least abstain, maybe back the Russians. And so any action under UN auspices is out of the question.

EMMA ALBERICI: Also, we'll go back to the other $64 million question: what will it take for Russia to back down?

RAJAN MENON: Well, at this point both sides, i.e. the US and the EU and Russia, need a face-saving formula.

I'm not an advisor to president Obama but one thing that occurs to me is to float to Mr Putin the idea of whether a neutral force can be deployed in Crimea to ease his alleged concerns that Russian lives are in danger.

The thing he wants now, which is much trickier, is for the elections to be held not in May but in December as agreed upon during the mediation that defused this crisis early on and for a government of national unity, which means essentially bringing back some members of the old guard. That's going to be very hard to do and if the US agrees to that it will look like Mr Obama's knuckling under. So this is still a tense stand-off.

EMMA ALBERICI: And what about that relationship between presidents Putin and Obama? What do the dynamics of those two characters on this stage tell us about how this geopolitical stoush is likely to play out from here on in?

RAJAN MENON: You know, I think leaders matter and so-called personal chemistry matters. I'm not sure that there's a warm relationship between Mr Putin and Mr Obama, but at the end of the day I think one has to look at what might, if you pardon the jargon, be called "structural factors", i.e. what is the situation on the ground militarily, politically, economically and how much manoeuvring room does each leader have? That is going to decide this, rather than whether the two men like each other and have a warm relationship and what have you.

EMMA ALBERICI: And presumably president Putin does care about the optics of all this at home in Russia. And as you mentioned earlier, the rouble is at a record low against the dollar. Interest rates have been put up, The stock exchange is down quite dramatically in the past few days. What are the Russians making of all of this?

RAJAN MENON: Well, to the first part of your observation, which I think is a very good one: Mr Putin's legitimacy or self-image, if you will, is that of a tough guy. And some of what he's doing - not all of it - is playing to the domestic audience and to burnish that image. That makes it harder for him to back down.

The other thing is that when he sees activities like this, i.e. wholesale political changes in "his neighbourhood", he has to ask himself the question: is it possible that there could be a domino effect that leads the same thing to happen in Russia? I'm not saying that that is imminent but that's certainly on his mind.

EMMA ALBERICI: Professor Menon, we're out of time. I thank you so much for being with us.